1. Technical Field
The present invention generally relates to a sensor or gage; and more particularly to a sensor or gage for a pump forming part of a pumping system.
2. Description of Related Problem
There are several commonly employed techniques to obtain an oil level of a bearing frame or of a rotating piece of equipment:
For example, a known sight glass oil level gage employs a small “star” shaped metal baffle with a hole, stamped or drilled in the center. This baffle is enclosed in a metal or plastic housing which screws into the bearing housing in such a way that the hole in the baffle is centered with the desired center line level of the oil. Outboard of the baffle is a transparent glass or plastic window, which is used to view the oil level. The disadvantage for the sight glass oil level gage is that it requires a person to visually check the oil.
In addition, an inductive or capacitive sensor is typically screwed into the bottom of the bearing housing. The sensor's length is such that it protrudes through the oil. The oil level is inferred by measuring the inductance of the sensor. This type of sensor can be used to automatically annunciate alarms or warnings on low or high oil level, when attached to a personal computer (PC), a supervisory control or data acquisition (SCADA) system or a distributed control system (DCS). The inductive or capacitive sensors must be available in many lengths to accommodate all of the different bearing house designs. To determine the oil level or change in oil level, a reference capacitance must be taken for each housing design. Most times this type of sensor is screwed into the oil drain hole plug connection, which necessitates removing wire, etc. when draining the oil. Otherwise, an extra plug connection on the bottom of the housing is required.
Other known level sensing techniques include that disclosed in U.S. Pat. No. 4,152,937, which provides for a liquid level sensor having a level mutual inductance probe with primary and secondary windings wound coextensively inside a closed end tubular protective housing; as well as that disclosed in U.S. Pat. No. 6,520,011, which provides for a powder detecting capacitive type sensor having a sensor body having a pair of electrodes inside and a circuit that detects a change of capacitance between the electrodes so as to detect the existence of powder adjacent the sensor body, where the sensor is arranged on a wall of a powder tank.